Have you tried looking through the soundtrack? Also googling lyrics? Perhaps music recognition apps?
– HakaseSep 8 '16 at 3:17

1

There are no lyrics and I spent 4 hours searching every site with soundtrack listings. I'm currently trying a music recognition app, but no luck so far.
– Dooley_labsSep 8 '16 at 3:18

I've added an audio clip for reference. The audio recognition app had as much luck as I've had so far.
– Dooley_labsSep 8 '16 at 3:34

Are you sure those are official previews? I don't think I remember hearing that, but maybe I always skipped them. Make sure it's not a dub's own thing, coz then you might need to ask the dub crew about the track.
– HakaseSep 8 '16 at 3:53

@Hakase they're definitely official. Both versions are voiced by the correct voice actors. They play at the end of each episode, after the credits.
– Dooley_labsSep 8 '16 at 16:06